Forked-Crossing Metasurface for Multi-Band Polarization Conversion with Distinct Bandwidths

This study presents a reflective and highly efficient multi-band metasurface polarization converter based on a forked-crossing patch array. Both simulation and experimental results reveal that such a metasurface achieves polarization conversion ratio (PCR) exceeding 90% over five frequency bands of 4.71-5.44 GHz, 7.26-9.55 GHz, 11.62-12.6 GHz, 13.33-13.46 GHz, and 15.61-15.62 GHz with high conversion efficiency realized at five distinct resonances. The quality-factor (Q-factor) analysis of each band reveals a hybrid behavior. More specifically, the first and second bands exhibit relatively low Q factors of approximately 6.95 and 3.67, indicating wideband polarization conversion capability. The third band has a moderate Q factor of 12.35, while the fourth and fifth bands show high-Q resonances with Q factors of 103.04 and 1561.5, respectively, indicating sharp and selective frequency responses. This combination of wideband and high-Q narrowband responses makes the proposed design especially suitable for complex electromagnetic scenarios, such as multifunctional radar, communication, and sensing systems, where both broad frequency coverage and precise spectral control are simultaneously required.